title: Efficient gonio-imaging of optically variable devices by compound-eye image-capturing system.
abstract: In this paper, we propose a method for efficient gonio-imaging of optically variable devices (OVDs), which are applied as a counterfeit deterrence for valuable documents. A compound-eye image-capturing system composed by a microlens array, a signal separator, and an image sensor was used to capture directionally distributed light from OVDs after being collimated by a convex lens. Multiple images corresponding to different observation angles were obtained in the individual eyes of the system, simultaneously and independently. A demonstration involving a holographic grating provided 100 gonio images that exhibited sensitive color changes of the diffracted light according to the observation angle.
authors.affiliation: National Research Institute of Police Science, 6-3-1 Kashiwanoha, Kashiwa, Chiba 277-0882, Japan. akao@nrips.go.jp
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Akao
authors.forename: Rui
authors.initials: R
authors.lastname: Shogenji
authors.forename: Norimichi
authors.initials: N
authors.lastname: Tsumura
authors.forename: Masahiro
authors.initials: M
authors.lastname: Yamaguchi
authors.forename: Jun
authors.initials: J
authors.lastname: Tanida
mesh_terms: D000818:Animals; D054910:Compound Eye, Arthropod / Q000033:anatomy & histology*; D006068:Gonioscopy / Q000379:methods*; D006696:Holography; D021621:Imaging, Three-Dimensional / Q000379:methods*; D055096:Optical Devices